A Fully Differential DC-Capable RF SPDT Switch in SOI

This paper introduces the first fully differential SOI SPDT switch with true dc switching capability combined with broadband RF performance. The design operates from dc to 12 GHz while sustaining ±8 V common-mode voltage and handling 31 dBm differential RF power. A series–shunt topology with four stacked transistors per branch is combined with distributed dc tracking loops that bootstrap gate/body resistors up to 20 MHz, overcoming the low-frequency power-handling vs switching-speed trade-off. A start-up scheme enables ±12 V supply operation in a 3.3 V process. Measured results demonstrate sub-1 dB insertion loss and excellent linearity (>34 dBm IP1dB and ~60 dBm IP3), enabling robust switching of high-speed differential links and instrumentation paths requiring mixed dc and RF capability.